Transcript Word Equations

Word Equations
CH.3.c
Writing Formulas
 Reactions formulas represent what
occurs in a chemical reaction
 Reactants are the participants in a
chemical reaction
 Products are the new compounds
formed as a result of a chemical
reaction
Evidence?
 What are the four products that are
evidence of a chemical reaction?
Symbols
 Symbols indicate the conditions of a
reaction
 indicates the direction of the
reaction
s,l,g
indicate the state of matter
aq
indicates that the solution is
aqueous, dissolved in water
heat
heat is required to react
Writing Equations
 A word equation is used to describe a
chemical reaction
 Words describe the conditions, the
reactants and the products
 You must make sure that the
chemical formula is properly balanced
(the charge)
Steps
 Step 1: Highlight the important parts
of the word problem
 Step 2: Identify the reactants and
products
 Step 3: Write the formulas for the
chemicals
Practice
 Zinc and Lead (II) nitrate yield Zinc
nitrate and Lead
Practice
 Aluminum bromide and chlorine yield
aluminum chloride and bromine
Practice
 Sodium phosphate and calcium
chloride yield calcium phosphate and
sodium chloride
Practice
 Potassium chlorate when heated
yields potassium chloride and oxygen
gas
Practice
 Aluminum and hydrochloric acid yield
aluminum chloride and hydrogen gas
Practice
 Calcium hydroxide and phosphoric
acid yield calcium phosphate and
water
Practice
 Copper and sulfuric acid yield copper
(II) sulfate and water and sulfur
dioxide
Practice
 Hydrogen and nitrogen monoxide
yield water and nitrogen
Balancing Equations
Now that you have written the
equation, you must balance it.
Yeah!!!
The Law
 Law of Conservation of Mass
 Law of Definite Proportions
Balancing Equations
 Step 1:
 Step 2:
side
 Step 3:
 Step 4:
Write the equation
Count the Atoms on each
Balance the # of atoms
Verify
The Rules
 DO NOT TOUCH THE SUBSCRIPTS!!!!!
 The Coefficient is the number in front
of the compound formula
 Coefficients represent the ratio of
compounds
 Similar to the ratio of atoms in a
chemical formula
The trick is . . .
 Determine the number of each type
of atom on the reactant and product
sides.
 Balance a polyatomic ion as a single
unit if it remains the same on both
sides
 When in doubt, double it out
Practice, practice, practice
 ___H2 + ___O2 => ___H2O
___H3PO4 + ___KOH => ___K3PO4 +
___H2O
 ____K + ___B2O3 => ___K2O +
___B
____HCl + ____NaOH => ___NaCl +
____H2O
___Na + ___NaNO3 => ___Na2O +
___N2
 ___C + ___S8 => ___CS2
 __Na + ___O2 => ___Na2O2
 ___N2 + ___O2 => ___N2O5
___H3PO4 + ___Mg(OH)2 =>
___Mg3(PO4)2 + ___H2O
__NaOH + ___H2CO3 => ___Na2CO3 +
___H2O
___KOH + ___HBr => ___KBr +
___H2O